1. Field of the Invention
The present invention relates to a projection apparatus, a projection method, and a storage medium storing a program, suitable for a Digital Light Processing (DLP) (a registered trademark) projector apparatus, for example.
2. Description of the Related Art
Various projectors have been designed and commercialized which project color images in a field sequential manner by transmitting white light from a light source through a color wheel with a plurality of color filters for the respective colors arranged on a peripheral surface thereof to obtain colored light in a time division manner and using the light to project images for the respective colors.
As light source elements for such a projector, semiconductor light emitting elements such as light emitting diodes (LEDs) or laser diodes (LDs), which are excellent in power consumption, size, and the quantity of heat, have been expected to replace discharge lamps such as high-pressure mercury lamps which have been frequently used.
If these semiconductor light emitting elements are used as light sources for a projector, since each semiconductor light emitting element essentially emits light at a single wavelength, a plurality of semiconductor light emitting elements with different light emission wavelengths need to be combined together for use.
If a plurality of different types of semiconductor light emitting elements with different light emission wavelengths are used, luminance needs to be balanced among the different types of semiconductor light emitting elements. Thus, as in the case of an invention described in Jpn. Pat. Appln. KOKAI Publication No. 2010-152326, a technique has been proposed in which the chromaticity of source light based on a field sequential method is accurately kept consistent with a set content has been proposed.
According to the technique described in Jpn. Pat. Appln. KOKAI Publication No. 2010-152326, the brightness of each color is measured using an illuminance sensor, and based on the results of the measurement, the brightness is adjusted such that an accumulated chromaticity is equal to a target value.
However, the semiconductor light emitting element has its light emission wavelength varied with temperature, while having its sensitivity varied with the wavelength of incident light. Thus, a change in the temperature of any of the semiconductor light emitting elements serving as light sources changes a detected value from the illuminance sensor even with the level of an output from the semiconductor light emitting element unchanged. As a result, the balance among the colors of the projected image is disrupted.